It is not unusual for bolt heads, nuts, screws and the like used in the construction of various machines and structures to be placed in locations in which they are difficult to engage and turn with conventional tools. This situation is increasingly prevalent in the automotive field, as engines and transmission systems, as well as auxiliary and control systems become more complex and sophisticated, and engine compartments become smaller. In almost all fields the increased focus on increased efficiency, refinement, and space saving has been very beneficial for users, but has created problems for mechanics and technicians who service the machines and equipment, by limiting space and access. In many instances tools designed for use in less restricted environments are difficult, and often impossible, to use today.
Engaging and turning threaded fasteners such as bolts and nuts with a wrench is an increasingly common and vexing problem. The problem with fastener accessibility has been developing over time along with the developments and changes in design. Over that time, and throughout the changes that have occurred in design and fastener placement, the accessibility of fasteners with a rigid, fixed head wrench has diminished. Fasteners are sometimes found in locations in which direct access from the top is blocked, precluding the use of a conventional socket wrench; direct access with a straight conventional wrench is blocked; and in which clearance between the fastener and obstructions on at least one, and often all, sides of the fastener is very limited. One such environment is shown in FIGS. 1 and 2 of the accompanying drawings, which are intended to be illustrative and not limiting of the scope of the problem. In order to reach fasteners disposed in such locations it has become more and more common for mechanics and other technicians to spend time and effort removing components that block access, for the sole reason of gaining access to otherwise inaccessible fasteners. This practice is not only time consuming, but increases the risk of damage to parts or components that must be removed and replaced even though they are not otherwise involved in the service or repair operation being performed.
One approach that has been tried in an effort to overcome this problem is the use of wrenches with pivoting heads, in which the component engaging head is pivotally connected to the wrench handle so the plane of the head can be disposed at an angle to the handle. Examples of wrenches with pivoting heads from the prior art include:
Patent NumberTitlePatenteeU.S. Pat. No. 1,060,494WrenchReynoldsU.S. Pat. No. 1,805,298WrenchSchweigertU.S. Pat. No. 3,186,265Wrench Having AngularlyWenturineAdjustable Auxiliary HandleU.S. Pat. No. 3,779,107Ratchet Wrench ToolAveryHead PositionerU.S. Pat. No. 4,084,456WrenchPasbrigU.S. Pat. No. 4,794,829Ratchet-Type WrenchMesenboellerU.S. Pat. No. 5,870,932Swift WrenchBrookeU.S. Pat. No. 6,000,302Tool Having RotatableChiangDriving HeadU.S. Pat. No. 6,148,698Angle-Adjustable BoxHsichEnd WrenchU.S. Pat. No. 6,186,033Multi-Positional TurningFaro, Sr.Tool
These prior art designs do provide an articulation of the wrench head relative to the wrench handle, and serve to improve access in some situations, but each of the designs of the prior art suffers from disadvantages and drawbacks that continue to preclude access to fasteners in many situations that are becoming increasingly common. The disadvantages found in all prior art wrench designs relate in large part to the distance from the pivot point between the wrench head and handle, and the closest edge of the fastener engaging aperture in the wrench head. In some designs the length of extension of the wrench head, and/or the width of extension of the wrench head, beyond the outer edge of the engaged fastener is also a significant disadvantage.
In the Reynolds design, the wrench head is generally rectangular, of substantially greater length than width. The handle of the wrench widens substantially at the end to which the wrench head is attached, to form a wide fork, in which an extension member of the wrench head is received. A pivot pin extends through the two sides of the fork and the extension member to pivotally connect the head to the handle. A V-shaped notch extends into the head from the outer end, and is provided with a plurality of teeth along one side of the notch to allow the wrench head to engage fasteners of a variety of sizes. As a result, when a fastener at or near the lower limit of the sizes that can be accommodated by the wrench is engaged, the wrench head extends a great distance outward beyond the fastener and to each side of the fastener. The base of the notch is positioned a distance away from the pivot point of the head relative to the handle, creating a significant distance between the closest point of even the smallest fastener and the pivot point of the head. The head is indexed to be fixed and retained at certain rotational angles rather than being freely moveable.
Schweigert discloses an adjustable wrench head that is pivotally connected to a handle. The adjustment mechanism is disposed between the fastener engaging slot of the wrench head and the handle. The head includes an extension member that is engaged with a widened fork at the end of the handle and pinned in place. The distance between the pivot point and the fastener engaging slot is substantial, and the width of the head relative to the size of the fastener to be engaged is large, so that use of this wrench requires significant clearance around the fastener.
Wenturine discloses a ratchet-type box end head pivotally connected to a handle. The ratchet mechanism is disposed between the pivot pin connecting the head to the handle and the fastener engaging aperture in the head, which significantly increases the distance between that aperture and the pivot point. The rear portion of the head includes a slot within which a handle extension is inserted and pinned. This wrench requires significant clearance between a fastener and an adjacent obstruction.
Avery also discloses a wrench, of the socket drive type, with a ratchet mechanism disposed in the drive head, between the driver and the pivotal connection to the handle, creating a significant distance between the driver and the pivot point, and requiring significant clearance for use. The socket drive mechanism also inherently requires significant clearance above a fastener for use.
Pasbrig discloses an adjustable wrench in which the head is pivotally connected to an extension member, which is itself pivotally connected to a handle. The head of the Pasbrig wrench is pivotable in the plane of the head, and is also pivotable in the other direction relative to the handle. The structure used to accomplish this dual pivoting movement, as well as the structure for adjusting the wrench for different fastener sizes, results in the fastener engaging aperture being placed a substantial distance from even the closest pivot point. Significant clearance is required for use of this wrench.
Mesenhoeller provides a ratchet-type socket driver, with the driver head pivotally connected to a handle. An extension from the driver head is received and pinned in a widened fork formed in the handle The size of the ratchet mechanism, plus the length of the member extending between the head and the handle results in placement of the driver at a substantial distance from the pivot point. The ratchet mechanism also increases the width of the head. Significant clearance in all directions is required for use of this wrench.
Brooke shows an open end wrench in which the wrench head is pivotally connected to a handle so as to rotate in the plane of the head. The distance between the fastener engaging aperture and the pivot point is significant relative to the size of the aperture. The position of the head is fixed in a limited number of indexed positions.
Chiang also discloses a ratchet-type socket driver head pivotally connected to a handle. This wrench suffers from the same inherent disadvantages and large clearance requirements as discussed above with regard to other socket driver designs.
Hsich discloses a box end wrench head pivotally connected to a handle. The length of the wrench head is approximately twice the diameter of the fastener engaging aperture, and the pivot point is a substantial distance from that aperture, so that a significant clearance around a fastener is required for the use of this wrench.
Faro, Sr. discloses a wrench in which a wrench head is pivotally connected to a handle, with a long member extending between the wrench head and the connection to the handle. The length of the extension member is greater than the dimension of the opening of the fastener engaging aperture, so that significant clearance between fastener and obstruction is required for use of the wrench.
It can be readily seen that these wrench designs and others of the prior art, cannot be used to access and turn fasteners in many tightly confined spaces, such as but not limited to those illustrated in FIGS. 1 and 2. There remains a need for an articulated wrench that can be effectively used when only minimal clearance is available in all directions between the fastener component to be engaged and turned and adjacent structures.